Comparative Raman Study of Carbon Nanotubes Prepared by D.C. Arc Discharge and Catalytic Methods

The Raman spectra of carbon nanotubes prepared by catalytic (C‐CNT) and d.c. arc discharge (D‐CNT) methods are reported. A previously unnoticed third‐order Raman peak at ca. 4248 cm‐1 was observed in the Raman spectrum of D‐CNT. The Raman features of D‐CNT and C‐CNT are similar to those of highly oriented pyrolytic graphite (HOPG) and active carbon, respectively. The data also suggest that the increase in disorder in D‐CNT compared with HOPG is due to structural defects in D‐CNT. © 1997 by John Wiley & Sons, Ltd.